In general, swimming pool water is filtered by means of a filtering cartridge mounted in combination with the water suction and delivery system. This cartridge is most often made of a corrugated folded polyester canvas arranged radially along the generating lines of a central cylinder. The base of this cartridge communicates with the suction system in particular in order to filter the water which may arrive from the outside of the said cartridge in order to cross its walls. Although the results obtained from a filtering quality point of view may be considered as satisfactory, this type of filter does have certain disadvantages. In fact, the cartridge gets dirty quite quickly and it is difficult to clean. In particular, substantial difficulties arise when removing the cartridge considering it is heavy.
Finally, these filtering cartridges make up a compact with a relatively high cost price and are somewhat fragile. Besides, as indicated, the filtering device is used for swimming pool water. With this in mind, the problem the invention intends to solve is to provide the filtering of liquid in a natural way, by gravity and not under pressure. In fact, pressurized filtering requires specific implementing means which would be totally unsuitable in the case of the application envisaged. For example, the U.S. Pat. No. 4,818,398 may be mentioned as this shows a filtering component arranged in a support which must be fitted with numerous accessories including a cover which is adapted to be completely tight taking the very high pressure forces generated with this type of filtering into consideration.
Furthermore, systems providing gravity filtering have been proposed. However, in this case, considering the means used to obtain satisfactory filtering, a very large filtering surface is required, preventing them from being used for filtering swimming pool water.